The present invention generally relates to fluid control valves, and more particularly, to a thermostatic control valve that operates more reliably throughout a wide range of flow rates.
Thermostatic control valves for fluid systems, especially hot water systems, have been known for years. These valves are used to set a maximum temperature for a fluid in a system to attain. As such, they are commonly used in hot water feed lines for bath and shower applications in order to prevent scalding by a user of the system. The operation of these type vales is relatively straightforward.
Typically, these valves use some sort of thermostatic element, commonly referred to in the art as a xe2x80x9cmotorxe2x80x9d, that is designed to move in certain direction based upon increases or decreases in temperature of the fluid passing around them. These elements are disposed within a fluid passage in the interior of the valve body and are typically biased in one direction by a spring. The thermal element, or motor, serves to operate a closing element that moves within the valve body to close off the valve so as to prevent the flow of hot water through the valve. In this manner, these valves may be used to temper a hot water supply to prevent inadvertent scalding by a user of the water system, which may occur when the fluid system is temporarily purged of cold water.
One type of thermostatic control valve that is exemplary of thermostatically controlled valves in the art, is described in U.S. Pat. No. 4,299,354, issued November 1, 1981. In this valve, a thermally responsive motor is formed as a cylindrical member that is biased into an open position. The motor is positioned within the flow passage of the valve within the body of the valve. Separate hot and cold water inlets are provided in the valve body so that respective amounts of hot and cold water enter the valve body and may be mixed together before the combined water exits the valve body. The passages present in the body of this valve that direct the water from the inlets into the valve flow passage are positioned around the edge of the flow passage and are not directed toward the thermal motor. As such, at low water flows through the valve, hot water may enter the valve body and travel through the valve without coming directly into contact with the thermal motor. Thus, there exists the risk in valve constructions such as this, that the thermal motor may not sense a change in temperature such as may occur when cold water is suddenly purged from the system, resulting in scalding to a user.
The present invention is directed to an improved thermally responsive valve that overcomes the aforementioned shortcomings.
Accordingly, it is a general object of the present invention to provide an improved thermally responsive valve that operates reliably at low flow conditions.
Another object of the present invention is to provide a thermal control valve that incorporates a dynamic water directing member that restricts the diameter of the flow passage in which the thermal motor of the valve sits without unduly restricting the flow of water through the flow passage.
A further object of the present invention is to provide a thermal control valve having a valve body and a thermal motor disposed longitudinally therein within a longitudinal flow passage of the valve, and the flow passage including a flow directing member mounted thereto having a generally frusto-conical shape that forms a flow restriction within the flow passage, the flow-directing member being formed from a flexible material that expands radially outwardly under pressure of water passing through the valve body flow passage, the flow-directing member having a diameter that changes in response to the flow of water through the valve body flow passage.
Yet another object of the present invention is to provide an improved thermally actuated valve having a central flow passage extending through a body of the valve, a thermal motor disposed within the flow passage and movable between at least first and second positions in which the valve flow passage is open and closed, and a flexible flow-directing member that directs water entering the flow passage against the exterior of the thermal motor at all water pressures, the flow-directing member having an expandable diameter that expands from a minimum diameter to a maximum diameter.
The present invention accomplishes these and other objects through its novel and unique structure. As evidence by the preferred embodiment of the invention, a valve assembly is provided having a plurality of parts, that cooperatively define a valve body having at least two inlets for receiving incoming hot and cold water, an outlet for the water, mixed or otherwise, to flow out the valve, a thermal motor disposed in the valve passage and movable between open and closed positions in response to the temperature of the water flowing into the valve, and a flow-directing member that directs the flow of water entering the valve at the exterior of the thermal motor so that the motor can accurately respond to the temperature of the water at all pressures.
In an important aspect of the present invention, the flow-directing member is a xe2x80x9cdynamicxe2x80x9d member, meaning that it changes shape in response to the pressure differential through the valve. In its normal condition, the flow-directing member has a shape similar to a truncated cone, or a frusto-conical configuration with a first diameter that is slightly larger than the diameter of the thermal motor. The flow-directing member is expandable under water pressure and is capable of expanding to a diameter much greater than its first diameter so as not to unduly restrict the flow of water passing through the valve.
The flow-directing member is preferably formed of rubber or other similar elastomeric material and it has a base for supporting it within a holder and a conical portion that extends from the base. The conical portion is corrugated so that it can flex and the diameter of the conical portion can expand to a second maximum diameter to permit the unimpeded passage of water through the valve at high flows.
These and other objects, features and advantages of the present invention will be clearly understood through a consideration of the following detailed description.